From: Ma Ke Date: Tue, 12 Aug 2025 07:19:32 +0000 (+0800) Subject: drm/mediatek: Fix device/node reference count leaks in mtk_drm_get_all_drm_priv X-Git-Tag: v6.16.5~15 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=fae58d0155a979a8c414bbc12db09dd4b2f910d0;p=thirdparty%2Fkernel%2Fstable.git drm/mediatek: Fix device/node reference count leaks in mtk_drm_get_all_drm_priv commit 1f403699c40f0806a707a9a6eed3b8904224021a upstream. Using device_find_child() and of_find_device_by_node() to locate devices could cause an imbalance in the device's reference count. device_find_child() and of_find_device_by_node() both call get_device() to increment the reference count of the found device before returning the pointer. In mtk_drm_get_all_drm_priv(), these references are never released through put_device(), resulting in permanent reference count increments. Additionally, the for_each_child_of_node() iterator fails to release node references in all code paths. This leaks device node references when loop termination occurs before reaching MAX_CRTC. These reference count leaks may prevent device/node resources from being properly released during driver unbind operations. As comment of device_find_child() says, 'NOTE: you will need to drop the reference with put_device() after use'. Cc: stable@vger.kernel.org Fixes: 1ef7ed48356c ("drm/mediatek: Modify mediatek-drm for mt8195 multi mmsys support") Signed-off-by: Ma Ke Reviewed-by: CK Hu Link: https://patchwork.kernel.org/project/dri-devel/patch/20250812071932.471730-1-make24@iscas.ac.cn/ Signed-off-by: Chun-Kuang Hu Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c b/drivers/gpu/drm/mediatek/mtk_drm_drv.c index 7c0c12dde4885..34131ae2c207d 100644 --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c @@ -388,19 +388,19 @@ static bool mtk_drm_get_all_drm_priv(struct device *dev) of_id = of_match_node(mtk_drm_of_ids, node); if (!of_id) - continue; + goto next_put_node; pdev = of_find_device_by_node(node); if (!pdev) - continue; + goto next_put_node; drm_dev = device_find_child(&pdev->dev, NULL, mtk_drm_match); if (!drm_dev) - continue; + goto next_put_device_pdev_dev; temp_drm_priv = dev_get_drvdata(drm_dev); if (!temp_drm_priv) - continue; + goto next_put_device_drm_dev; if (temp_drm_priv->data->main_len) all_drm_priv[CRTC_MAIN] = temp_drm_priv; @@ -412,10 +412,17 @@ static bool mtk_drm_get_all_drm_priv(struct device *dev) if (temp_drm_priv->mtk_drm_bound) cnt++; - if (cnt == MAX_CRTC) { - of_node_put(node); +next_put_device_drm_dev: + put_device(drm_dev); + +next_put_device_pdev_dev: + put_device(&pdev->dev); + +next_put_node: + of_node_put(node); + + if (cnt == MAX_CRTC) break; - } } if (drm_priv->data->mmsys_dev_num == cnt) {